This is how the Princesses told the foals goes in The Quest for the Skylanders Part 2.
Later, In Canterlot.
Princess Celestia: And that's the whole thing, Yuna, I'm truly sorry we didn't tell you sooner, It was for the sake of your safety.
Princess Yuna: It's okay, Aunt Celestia, You were only trying to help.
Princess Sharon: We're just glad to do so. Right, Celestia.
Princess Celestia: And how, My daughter.
Duck: Yuna, You seem to be taking this remarkably well.
Hiro: How do we stop Thaddeus E. Klang and Feathers McGraw from taking over Skylands?
Snowdrop: How will we win?
EVE: (comforts Snowdrop)
Flain: There's gotta be a way.
Princess Yuna: There's always a way, Will you and Dobby wish us luck, Draco?
Draco: Long ago, when man was young and the dragon already old, the wisest of our race took pity on man. He gathered together all the dragons making them vow to watch over man always. And at the moment of his death, the night became alive with those stars. And thus was born the dragons' heaven. But when we die, not all dragons are admitted to this shining place. No, we have to earn it. And if we don't our spirit disappears as if we never were. And that's why l shared my life force with a dying elf so l would reunite man and dragon and all with human thoughts and emotions and ensure my place among my ancient brothers of the sky.
Princess Yuna: And your sacrifice for Dobby was your righteousness.
Draco: Exactly. Yuna, We will go with you and your friends and your guardians.
Princess Luna: Be careful, Yuna.
Princess Yuna: I will, Mama. Are you and the Skylanders ready, Spyro?
Spyro: Ready and steady!
Princess Yuna: Are you and the Minis ready, Spry?
Spry: Ready than you are.
Princess Yuna: Are you and the Giants ready, Tree Rex?
Tree Rex: OH, Yeah!!!
Princess Yuna: Are you and the SWAP Force ready, Wash Buckler?
Wash Buckler: All Set!
Princess Yuna: Are you and the Trap Team Ready, Snap Shot?
Snap Shot: Yes, We're ready!
Princess Yuna: Alright then, Let's go!